title: Cluster formation in ferrofluids induced by holographic optical tweezers.
abstract: Holographic optical tweezers were used to show the interaction between a strongly focused laser beam and magnetic nanoparticles in ferrofluid. When the light intensity was high enough, magnetic nanoparticles were removed from the beam center and formed a dark ring. The same behavior was observed when focusing vortex or Bessel beams. The interactions between two or more separated rings of magnetic nanoparticles created by independent optical traps were also observed.
authors.forename: Jan
authors.initials: J
authors.lastname: Masajada
authors.forename: Marcin
authors.initials: M
authors.lastname: Bacia
authors.forename: Sławomir
authors.initials: S
authors.lastname: Drobczyński